Transmission of group handover message

ABSTRACT

Methods, apparatuses, and computer readable medium for enabling an efficient group handover mechanism that has less signaling overhead than single UE handover are provided. An example method at a base station includes transmitting a group handover request for the group of UEs to a target base station. The method further includes receiving a group handover acknowledgment from the target base station. The method further includes transmitting a group handover message to the group of UEs.

CROSS REFERENCE TO RELATED APPLICATION(S)

This application claims the benefit of and priority to U.S. ProvisionalApplication Ser. No. 63/061,640, entitled “TRANSMISSION OF GROUPHANDOVER MESSAGE” and filed on Aug. 5, 2020, which is expresslyincorporated by reference herein in its entirety.

BACKGROUND Technical Field

The present disclosure relates generally to communication systems, andmore particularly, to a wireless communication system with a handovermechanism.

Introduction

Wireless communication systems are widely deployed to provide varioustelecommunication services such as telephony, video, data, messaging,and broadcasts. Typical wireless communication systems may employmultiple-access technologies capable of supporting communication withmultiple users by sharing available system resources. Examples of suchmultiple-access technologies include code division multiple access(CDMA) systems, time division multiple access (TDMA) systems, frequencydivision multiple access (FDMA) systems, orthogonal frequency divisionmultiple access (OFDMA) systems, single-carrier frequency divisionmultiple access (SC-FDMA) systems, and time division synchronous codedivision multiple access (TD-SCDMA) systems.

These multiple access technologies have been adopted in varioustelecommunication standards to provide a common protocol that enablesdifferent wireless devices to communicate on a municipal, national,regional, and even global level. An example telecommunication standardis 5G New Radio (NR). 5G NR is part of a continuous mobile broadbandevolution promulgated by Third Generation Partnership Project (3GPP) tomeet new requirements associated with latency, reliability, security,scalability (e.g., with Internet of Things (IoT)), and otherrequirements. 5G NR includes services associated with enhanced mobilebroadband (eMBB), massive machine type communications (mMTC), andultra-reliable low latency communications (URLLC). Some aspects of 5G NRmay be based on the 4G Long Term Evolution (LTE) standard. There existsa need for further improvements in 5G NR technology. These improvementsmay also be applicable to other multi-access technologies and thetelecommunication standards that employ these technologies.

SUMMARY

The following presents a simplified summary of one or more aspects inorder to provide a basic understanding of such aspects. This summary isnot an extensive overview of all contemplated aspects, and is intendedto neither identify key or critical elements of all aspects nordelineate the scope of any or all aspects. Its sole purpose is topresent some concepts of one or more aspects in a simplified form as aprelude to the more detailed description that is presented later.

Satellites may be integrated in a 5G communication system to facilitatethe communication between a base station and a UE. For example, atransparent satellite that performs amplification, spatial filtering, orfrequency conversion may relay communication transmitted from a basestation to UEs. When a transparent satellite moves, it may need toswitch the feeder link because the base station associated with thefeeder link may be out of coverage for the satellite. Therefore, UEsserved by the satellite may need to be handed over to another basestation. Existing handover mechanisms that handover each UE individuallyis inefficient for this type of handover.

Methods, apparatuses, and computer readable medium for enabling anefficient group handover mechanism that has less signaling overhead thansingle user equipment (UE) handover are provided.

In one aspect of the disclosure, a method, a computer-readable medium,and an apparatus are provided for wireless communication at a basestation. The base station transmits a group handover request for thegroup of UEs to a target base station and receives a group handoveracknowledgment from the target base station. The base station transmitsa group handover message to the group of UEs.

In another aspect of the disclosure, a method, a computer-readablemedium, and an apparatus are provided for wireless communication at aUE. The UE receives a group handover message comprising RRCconfiguration for one or more UEs transmitted to a group of UEscomprising the one or more UEs from the source base station and connectsto a target base station using the RRC configuration based on the grouphandover message.

To the accomplishment of the foregoing and related ends, the one or moreaspects comprise the features hereinafter fully described andparticularly pointed out in the claims. The following description andthe annexed drawings set forth in detail certain illustrative featuresof the one or more aspects. These features are indicative, however, ofbut a few of the various ways in which the principles of various aspectsmay be employed, and this description is intended to include all suchaspects and their equivalents.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating an example of a wireless communicationssystem and an access network.

FIG. 2A is a diagram illustrating an example of a first frame, inaccordance with various aspects of the present disclosure.

FIG. 2B is a diagram illustrating an example of DL channels within asubframe, in accordance with various aspects of the present disclosure.

FIG. 2C is a diagram illustrating an example of a second frame, inaccordance with various aspects of the present disclosure.

FIG. 2D is a diagram illustrating an example of UL channels within asubframe, in accordance with various aspects of the present disclosure.

FIG. 3 is a diagram illustrating an example of a base station and userequipment (UE) in an access network.

FIGS. 4A and 4B illustrate example wireless communication environmentswith a satellite.

FIG. 5 is an example communication flow between a group of UEs and abase station that communicates via a satellite.

FIG. 6 is a flowchart of a method of wireless communication of a basestation.

FIG. 7 is a flowchart of a method of wireless communication of a UE.

FIG. 8 is a diagram illustrating an example of a hardware implementationfor an example apparatus.

FIG. 9 is a flowchart of a method of wireless communication of a UE.

FIG. 10 is a flowchart of a method of wireless communication of a UE.

FIG. 11 is a diagram illustrating an example of a hardwareimplementation for an example apparatus.

DETAILED DESCRIPTION

The detailed description set forth below in connection with the appendeddrawings is intended as a description of various configurations and isnot intended to represent the only configurations in which the conceptsdescribed herein may be practiced. The detailed description includesspecific details for the purpose of providing a thorough understandingof various concepts. However, it will be apparent to those skilled inthe art that these concepts may be practiced without these specificdetails. In some instances, well known structures and components areshown in block diagram form in order to avoid obscuring such concepts.

Several aspects of telecommunication systems will now be presented withreference to various apparatus and methods. These apparatus and methodswill be described in the following detailed description and illustratedin the accompanying drawings by various blocks, components, circuits,processes, algorithms, etc. (collectively referred to as “elements”).These elements may be implemented using electronic hardware, computersoftware, or any combination thereof. Whether such elements areimplemented as hardware or software depends upon the particularapplication and design constraints imposed on the overall system.

By way of example, an element, or any portion of an element, or anycombination of elements may be implemented as a “processing system” thatincludes one or more processors. Examples of processors includemicroprocessors, microcontrollers, graphics processing units (GPUs),central processing units (CPUs), application processors, digital signalprocessors (DSPs), reduced instruction set computing (RISC) processors,systems on a chip (SoC), baseband processors, field programmable gatearrays (FPGAs), programmable logic devices (PLDs), state machines, gatedlogic, discrete hardware circuits, and other suitable hardwareconfigured to perform the various functionality described throughoutthis disclosure. One or more processors in the processing system mayexecute software. Software shall be construed broadly to meaninstructions, instruction sets, code, code segments, program code,programs, subprograms, software components, applications, softwareapplications, software packages, routines, subroutines, objects,executables, threads of execution, procedures, functions, etc., whetherreferred to as software, firmware, middleware, microcode, hardwaredescription language, or otherwise.

Accordingly, in one or more example embodiments, the functions describedmay be implemented in hardware, software, or any combination thereof. Ifimplemented in software, the functions may be stored on or encoded asone or more instructions or code on a computer-readable medium.Computer-readable media includes computer storage media. Storage mediamay be any available media that can be accessed by a computer. By way ofexample, and not limitation, such computer-readable media can comprise arandom-access memory (RAM), a read-only memory (ROM), an electricallyerasable programmable ROM (EEPROM), optical disk storage, magnetic diskstorage, other magnetic storage devices, combinations of the types ofcomputer-readable media, or any other medium that can be used to storecomputer executable code in the form of instructions or data structuresthat can be accessed by a computer.

While aspects and implementations are described in this application byillustration to some examples, those skilled in the art will understandthat additional implementations and use cases may come about in manydifferent arrangements and scenarios. Innovations described herein maybe implemented across many differing platform types, devices, systems,shapes, sizes, and packaging arrangements. For example, implementationsand/or uses may come about via integrated chip implementations and othernon-module-component based devices (e.g., end-user devices, vehicles,communication devices, computing devices, industrial equipment,retail/purchasing devices, medical devices, artificial intelligence(AI)-enabled devices, etc.). While some examples may or may not bespecifically directed to use cases or applications, a wide assortment ofapplicability of described innovations may occur. Implementations mayrange a spectrum from chip-level or modular components to non-modular,non-chip-level implementations and further to aggregate, distributed, ororiginal equipment manufacturer (OEM) devices or systems incorporatingone or more aspects of the described innovations. In some practicalsettings, devices incorporating described aspects and features may alsoinclude additional components and features for implementation andpractice of claimed and described aspect. For example, transmission andreception of wireless signals necessarily includes a number ofcomponents for analog and digital purposes (e.g., hardware componentsincluding antenna, RF-chains, power amplifiers, modulators, buffer,processor(s), interleaver, adders/summers, etc.). It is intended thatinnovations described herein may be practiced in a wide variety ofdevices, chip-level components, systems, distributed arrangements,aggregated or disaggregated components, end-user devices, etc. ofvarying sizes, shapes, and constitution.

FIG. 1 is a diagram illustrating an example of a wireless communicationssystem and an access network 100. The wireless communications system(also referred to as a wireless wide area network (WWAN)) includes basestations 102, UEs 104, an Evolved Packet Core (EPC) 160, and anothercore network 190 (e.g., a 5G Core (5GC)). The base stations 102 mayinclude macrocells (high power cellular base station) and/or small cells(low power cellular base station). The macrocells include base stations.The small cells include femtocells, picocells, and microcells.

The base stations 102 configured for 4G LTE (collectively referred to asEvolved Universal Mobile Telecommunications System (UMTS) TerrestrialRadio Access Network (E-UTRAN)) may interface with the EPC 160 throughfirst backhaul links 132 (e.g., 51 interface). The base stations 102configured for 5G NR (collectively referred to as Next Generation RAN(NG-RAN)) may interface with core network 190 through second backhaullinks 184. In addition to other functions, the base stations 102 mayperform one or more of the following functions: transfer of user data,radio channel ciphering and deciphering, integrity protection, headercompression, mobility control functions (e.g., handover, dualconnectivity), inter-cell interference coordination, connection setupand release, load balancing, distribution for non-access stratum (NAS)messages, NAS node selection, synchronization, radio access network(RAN) sharing, multimedia broadcast multicast service (MBMS), subscriberand equipment trace, RAN information management (RIM), paging,positioning, and delivery of warning messages. The base stations 102 maycommunicate directly or indirectly (e.g., through the EPC 160 or corenetwork 190) with each other over third backhaul links 134 (e.g., X2interface). The first backhaul links 132, the second backhaul links 184,and the third backhaul links 134 may be wired or wireless.

The base stations 102 may wirelessly communicate with the UEs 104. Eachof the base stations 102 may provide communication coverage for arespective geographic coverage area 110. There may be overlappinggeographic coverage areas 110. For example, the small cell 102′ may havea coverage area 110′ that overlaps the coverage area 110 of one or moremacro base stations 102. A network that includes both small cell andmacrocells may be known as a heterogeneous network. A heterogeneousnetwork may also include Home Evolved Node Bs (eNBs) (HeNBs), which mayprovide service to a restricted group known as a closed subscriber group(CSG). The communication links 120 between the base stations 102 and theUEs 104 may include uplink (UL) (also referred to as reverse link)transmissions from a UE 104 to a base station 102 and/or downlink (DL)(also referred to as forward link) transmissions from a base station 102to a UE 104. The communication links 120 may use multiple-input andmultiple-output (MIMO) antenna technology, including spatialmultiplexing, beamforming, and/or transmit diversity. The communicationlinks may be through one or more carriers. The base stations 102/UEs 104may use spectrum up to Y MHz (e.g., 5, 10, 15, 20, 100, 400, etc. MHz)bandwidth per carrier allocated in a carrier aggregation of up to atotal of Yx MHz (x component carriers) used for transmission in eachdirection. The carriers may or may not be adjacent to each other.Allocation of carriers may be asymmetric with respect to DL and UL(e.g., more or fewer carriers may be allocated for DL than for UL). Thecomponent carriers may include a primary component carrier and one ormore secondary component carriers. A primary component carrier may bereferred to as a primary cell (PCell) and a secondary component carriermay be referred to as a secondary cell (SCell).

Certain UEs 104 may communicate with each other using device-to-device(D2D) communication link 158. The D2D communication link 158 may use theDL/UL WWAN spectrum. The D2D communication link 158 may use one or moresidelink channels, such as a physical sidelink broadcast channel(PSBCH), a physical sidelink discovery channel (PSDCH), a physicalsidelink shared channel (PSSCH), and a physical sidelink control channel(PSCCH). D2D communication may be through a variety of wireless D2Dcommunications systems, such as for example, WiMedia, Bluetooth, ZigBee,Wi-Fi based on the Institute of Electrical and Electronics Engineers(IEEE) 802.11 standard, LTE, or NR.

The wireless communications system may further include a Wi-Fi accesspoint (AP) 150 in communication with Wi-Fi stations (STAs) 152 viacommunication links 154, e.g., in a 5 GHz unlicensed frequency spectrumor the like. When communicating in an unlicensed frequency spectrum, theSTAs 152/AP 150 may perform a clear channel assessment (CCA) prior tocommunicating in order to determine whether the channel is available.

The small cell 102′ may operate in a licensed and/or an unlicensedfrequency spectrum. When operating in an unlicensed frequency spectrum,the small cell 102′ may employ NR and use the same unlicensed frequencyspectrum (e.g., 5 GHz, or the like) as used by the Wi-Fi AP 150. Thesmall cell 102′, employing NR in an unlicensed frequency spectrum, mayboost coverage to and/or increase capacity of the access network.

The electromagnetic spectrum is often subdivided, based onfrequency/wavelength, into various classes, bands, channels, etc. In 5GNR, two initial operating bands have been identified as frequency rangedesignations FR1 (410 MHz-7.125 GHz) and FR2 (24.25 GHz-52.6 GHz).Although a portion of FR1 is greater than 6 GHz, FR1 is often referredto (interchangeably) as a “sub-6 GHz” band in various documents andarticles. A similar nomenclature issue sometimes occurs with regard toFR2, which is often referred to (interchangeably) as a “millimeter wave”band in documents and articles, despite being different from theextremely high frequency (EHF) band (30 GHz-300 GHz) which is identifiedby the International Telecommunications Union (ITU) as a “millimeterwave” band.

The frequencies between FR1 and FR2 are often referred to as mid-bandfrequencies. Recent 5G NR studies have identified an operating band forthese mid-band frequencies as frequency range designation FR3 (7.125GHz-24.25 GHz). Frequency bands falling within FR3 may inherit FR1characteristics and/or FR2 characteristics, and thus may effectivelyextend features of FR1 and/or FR2 into mid-band frequencies. Inaddition, higher frequency bands are currently being explored to extend5G NR operation beyond 52.6 GHz. For example, three higher operatingbands have been identified as frequency range designations FR4a or FR4-1(52.6 GHz-71 GHz), FR4 (52.6 GHz-114.25 GHz), and FR5 (114.25 GHz-300GHz). Each of these higher frequency bands falls within the EHF band.

With the above aspects in mind, unless specifically stated otherwise, itshould be understood that the term “sub-6 GHz” or the like if usedherein may broadly represent frequencies that may be less than 6 GHz,may be within FR1, or may include mid-band frequencies. Further, unlessspecifically stated otherwise, it should be understood that the term“millimeter wave” or the like if used herein may broadly representfrequencies that may include mid-band frequencies, may be within FR2,FR4, FR4-a or FR4-1, and/or FR5, or may be within the EHF band.

A base station 102, whether a small cell 102′ or a large cell (e.g.,macro base station), may include and/or be referred to as an eNB, gNodeB(gNB), or another type of base station. Some base stations, such as gNB180 may operate in a traditional sub 6 GHz spectrum, in millimeter wavefrequencies, and/or near millimeter wave frequencies in communicationwith the UE 104. When the gNB 180 operates in millimeter wave or nearmillimeter wave frequencies, the gNB 180 may be referred to as amillimeter wave base station. The millimeter wave base station 180 mayutilize beamforming 182 with the UE 104 to compensate for the path lossand short range. The base station 180 and the UE 104 may each include aplurality of antennas, such as antenna elements, antenna panels, and/orantenna arrays to facilitate the beamforming.

The base station 180 may transmit a beamformed signal to the UE 104 inone or more transmit directions 182′. The UE 104 may receive thebeamformed signal from the base station 180 in one or more receivedirections 182″. The UE 104 may also transmit a beamformed signal to thebase station 180 in one or more transmit directions. The base station180 may receive the beamformed signal from the UE 104 in one or morereceive directions. The base station 180/UE 104 may perform beamtraining to determine the best receive and transmit directions for eachof the base station 180/UE 104. The transmit and receive directions forthe base station 180 may or may not be the same. The transmit andreceive directions for the UE 104 may or may not be the same.

The EPC 160 may include a Mobility Management Entity (MME) 162, otherMMEs 164, a Serving Gateway 166, a Multimedia Broadcast MulticastService (MBMS) Gateway 168, a Broadcast Multicast Service Center (BM-SC)170, and a Packet Data Network (PDN) Gateway 172. The MME 162 may be incommunication with a Home Subscriber Server (HSS) 174. The MME 162 isthe control node that processes the signaling between the UEs 104 andthe EPC 160. Generally, the MME 162 provides bearer and connectionmanagement. All user Internet protocol (IP) packets are transferredthrough the Serving Gateway 166, which itself is connected to the PDNGateway 172. The PDN Gateway 172 provides UE IP address allocation aswell as other functions. The PDN Gateway 172 and the BM-SC 170 areconnected to the IP Services 176. The IP Services 176 may include theInternet, an intranet, an IP Multimedia Subsystem (IMS), a PS StreamingService, and/or other IP services. The BM-SC 170 may provide functionsfor MBMS user service provisioning and delivery. The BM-SC 170 may serveas an entry point for content provider MBMS transmission, may be used toauthorize and initiate MBMS Bearer Services within a public land mobilenetwork (PLMN), and may be used to schedule MBMS transmissions. The MBMSGateway 168 may be used to distribute MBMS traffic to the base stations102 belonging to a Multicast Broadcast Single Frequency Network (MBSFN)area broadcasting a particular service, and may be responsible forsession management (start/stop) and for collecting eMBMS relatedcharging information.

The core network 190 may include an Access and Mobility ManagementFunction (AMF) 192, other AMFs 193, a Session Management Function (SMF)194, and a User Plane Function (UPF) 195. The AMF 192 may be incommunication with a Unified Data Management (UDM) 196. The AMF 192 isthe control node that processes the signaling between the UEs 104 andthe core network 190. Generally, the AMF 192 provides QoS flow andsession management. All user Internet protocol (IP) packets aretransferred through the UPF 195. The UPF 195 provides UE IP addressallocation as well as other functions. The UPF 195 is connected to theIP Services 197. The IP Services 197 may include the Internet, anintranet, an IP Multimedia Subsystem (IMS), a Packet Switch (PS)Streaming (PSS) Service, and/or other IP services.

The base station may include and/or be referred to as a gNB, Node B,eNB, an access point, a base transceiver station, a radio base station,a radio transceiver, a transceiver function, a basic service set (BSS),an extended service set (ESS), a transmit reception point (TRP), or someother suitable terminology. The base station 102 provides an accesspoint to the EPC 160 or core network 190 for a UE 104. Examples of UEs104 include a cellular phone, a smart phone, a session initiationprotocol (SIP) phone, a laptop, a personal digital assistant (PDA), asatellite radio, a global positioning system, a multimedia device, avideo device, a digital audio player (e.g., MP3 player), a camera, agame console, a tablet, a smart device, a wearable device, a vehicle, anelectric meter, a gas pump, a large or small kitchen appliance, ahealthcare device, an implant, a sensor/actuator, a display, or anyother similar functioning device. Some of the UEs 104 may be referred toas IoT devices (e.g., parking meter, gas pump, toaster, vehicles, heartmonitor, etc.). The UE 104 may also be referred to as a station, amobile station, a subscriber station, a mobile unit, a subscriber unit,a wireless unit, a remote unit, a mobile device, a wireless device, awireless communications device, a remote device, a mobile subscriberstation, an access terminal, a mobile terminal, a wireless terminal, aremote terminal, a handset, a user agent, a mobile client, a client, orsome other suitable terminology. In some scenarios, the term UE may alsoapply to one or more companion devices such as in a device constellationarrangement. One or more of these devices may collectively access thenetwork and/or individually access the network.

Referring again to FIG. 1, in certain aspects, the base station 102 or180 may include a group handover component 198 that configured toperform a group handover of a group of UEs 103 that includes at leasttwo UEs 104 to another base station 102 or 180. For example, if the basestation 102 or 180 communicates with a group of UEs 104 via thesatellite 121, as the satellite 121 moves out of coverage of the basestation 180, the base station 180 may hand over the group of UEs 104 toanother base station 102. The group handover component 198 may beconfigured to transmit a group handover request for the group of UEs 103to a target base station (e.g., base station 102 or 180), receive agroup handover acknowledgment from the target base station, and transmita group handover message to the group of UEs 103.

Each UE 104 served by the base station 102 or 180 may include a grouphandover message component 199 configured to receive a group handovermessage comprising RRC configuration for one or more UEs transmitted toa group of UEs comprising the one or more UEs from the source basestation connect to a target base station using the RRC configurationbased on the group handover message.

FIG. 2A is a diagram 200 illustrating an example of a first subframewithin a 5G NR frame structure. FIG. 2B is a diagram 230 illustrating anexample of DL channels within a 5G NR subframe. FIG. 2C is a diagram 250illustrating an example of a second subframe within a 5G NR framestructure. FIG. 2D is a diagram 280 illustrating an example of ULchannels within a 5G NR subframe. The 5G NR frame structure may befrequency division duplexed (FDD) in which for a particular set ofsubcarriers (carrier system bandwidth), subframes within the set ofsubcarriers are dedicated for either DL or UL, or may be time divisionduplexed (TDD) in which for a particular set of subcarriers (carriersystem bandwidth), subframes within the set of subcarriers are dedicatedfor both DL and UL. In the examples provided by FIGS. 2A, 2C, the 5G NRframe structure is assumed to be TDD, with subframe 4 being configuredwith slot format 28 (with mostly DL), where D is DL, U is UL, and F isflexible for use between DL/UL, and subframe 3 being configured withslot format 1 (with all UL). While subframes 3, 4 are shown with slotformats 1, 28, respectively, any particular subframe may be configuredwith any of the various available slot formats 0-61. Slot formats 0, 1are all DL, UL, respectively. Other slot formats 2-61 include a mix ofDL, UL, and flexible symbols. UEs are configured with the slot format(dynamically through DL control information (DCI), orsemi-statically/statically through radio resource control (RRC)signaling) through a received slot format indicator (SFI). Note that thedescription infra applies also to a 5G NR frame structure that is TDD.

FIGS. 2A-2D illustrate a frame structure, and the aspects of the presentdisclosure may be applicable to other wireless communicationtechnologies, which may have a different frame structure and/ordifferent channels. A frame (10 ms) may be divided into 10 equally sizedsubframes (1 ms). Each subframe may include one or more time slots.Subframes may also include mini-slots, which may include 7, 4, or 2symbols. Each slot may include 14 or 12 symbols, depending on whetherthe cyclic prefix (CP) is normal or extended. For normal CP, each slotmay include 14 symbols, and for extended CP, each slot may include 12symbols. The symbols on DL may be CP orthogonal frequency divisionmultiplexing (OFDM) (CP-OFDM) symbols. The symbols on UL may be CP-OFDMsymbols (for high throughput scenarios) or discrete Fourier transform(DFT) spread OFDM (DFT-s-OFDM) symbols (also referred to as singlecarrier frequency-division multiple access (SC-FDMA) symbols) (for powerlimited scenarios; limited to a single stream transmission). The numberof slots within a subframe is based on the CP and the numerology. Thenumerology defines the subcarrier spacing (SCS) and, effectively, thesymbol length/duration, which is equal to 1/SCS.

SCS Δf = 2^(μ) · Cyclic μ 15 [kHz] prefix 0 15 Normal 1 30 Normal 2 60Normal, Extended 3 120 Normal 4 240 Normal

For normal CP (14 symbols/slot), different numerologies μ 0 to 4 allowfor 1, 2, 4, 8, and 16 slots, respectively, per subframe. For extendedCP, the numerology 2 allows for 4 slots per subframe. Accordingly, fornormal CP and numerology μ, there are 14 symbols/slot and 2^(μ)slots/subframe. The subcarrier spacing may be equal to 2^(μ)*15 kHz,where μ is the numerology 0 to 4. As such, the numerology μ=0 has asubcarrier spacing of 15 kHz and the numerology μ=4 has a subcarrierspacing of 240 kHz. The symbol length/duration is inversely related tothe subcarrier spacing. FIGS. 2A-2D provide an example of normal CP with14 symbols per slot and numerology μ=2 with 4 slots per subframe. Theslot duration is 0.25 ms, the subcarrier spacing is 60 kHz, and thesymbol duration is approximately 16.67 μs. Within a set of frames, theremay be one or more different bandwidth parts (BWPs) (see FIG. 2B) thatare frequency division multiplexed. Each BWP may have a particularnumerology and CP (normal or extended).

A resource grid may be used to represent the frame structure. Each timeslot includes a resource block (RB) (also referred to as physical RBs(PRBs)) that extends 12 consecutive subcarriers. The resource grid isdivided into multiple resource elements (REs). The number of bitscarried by each RE depends on the modulation scheme.

As illustrated in FIG. 2A, some of the REs carry reference (pilot)signals (RS) for the UE. The RS may include demodulation RS (DM-RS)(indicated as R for one particular configuration, but other DM-RSconfigurations are possible) and channel state information referencesignals (CSI-RS) for channel estimation at the UE. The RS may alsoinclude beam measurement RS (BRS), beam refinement RS (BRRS), and phasetracking RS (PT-RS).

FIG. 2B illustrates an example of various DL channels within a subframeof a frame. The physical downlink control channel (PDCCH) carries DCIwithin one or more control channel elements (CCEs) (e.g., 1, 2, 4, 8, or16 CCEs), each CCE including six RE groups (REGs), each REG including 12consecutive REs in an OFDM symbol of an RB. A PDCCH within one BWP maybe referred to as a control resource set (CORESET). A UE is configuredto monitor PDCCH candidates in a PDCCH search space (e.g., common searchspace, UE-specific search space) during PDCCH monitoring occasions onthe CORESET, where the PDCCH candidates have different DCI formats anddifferent aggregation levels. Additional BWPs may be located at greaterand/or lower frequencies across the channel bandwidth. A primarysynchronization signal (PSS) may be within symbol 2 of particularsubframes of a frame. The PSS is used by a UE 104 to determinesubframe/symbol timing and a physical layer identity. A secondarysynchronization signal (SSS) may be within symbol 4 of particularsubframes of a frame. The SSS is used by a UE to determine a physicallayer cell identity group number and radio frame timing. Based on thephysical layer identity and the physical layer cell identity groupnumber, the UE can determine a physical cell identifier (PCI). Based onthe PCI, the UE can determine the locations of the DM-RS. The physicalbroadcast channel (PBCH), which carries a master information block(MIB), may be logically grouped with the PSS and SSS to form asynchronization signal (SS)/PBCH block (also referred to as SS block(SSB)). The MIB provides a number of RBs in the system bandwidth and asystem frame number (SFN). The physical downlink shared channel (PDSCH)carries user data, broadcast system information not transmitted throughthe PBCH such as system information blocks (SIBs), and paging messages.

As illustrated in FIG. 2C, some of the REs carry DM-RS (indicated as Rfor one particular configuration, but other DM-RS configurations arepossible) for channel estimation at the base station. The UE maytransmit DM-RS for the physical uplink control channel (PUCCH) and DM-RSfor the physical uplink shared channel (PUSCH). The PUSCH DM-RS may betransmitted in the first one or two symbols of the PUSCH. The PUCCHDM-RS may be transmitted in different configurations depending onwhether short or long PUCCHs are transmitted and depending on theparticular PUCCH format used. The UE may transmit sounding referencesignals (SRS). The SRS may be transmitted in the last symbol of asubframe. The SRS may have a comb structure, and a UE may transmit SRSon one of the combs. The SRS may be used by a base station for channelquality estimation to enable frequency-dependent scheduling on the UL.

FIG. 2D illustrates an example of various UL channels within a subframeof a frame. The PUCCH may be located as indicated in one configuration.The PUCCH carries uplink control information (UCI), such as schedulingrequests, a channel quality indicator (CQI), a precoding matrixindicator (PMI), a rank indicator (RI), and hybrid automatic repeatrequest (HARQ) acknowledgment (ACK) (HARQ-ACK) feedback (i.e., one ormore HARQ ACK bits indicating one or more ACK and/or negative ACK(NACK)). The PUSCH carries data, and may additionally be used to carry abuffer status report (BSR), a power headroom report (PHR), and/or UCI.

FIG. 3 is a block diagram of a base station 310 in communication with aUE 350 in an access network. In the DL, IP packets from the EPC 160 maybe provided to a controller/processor 375. The controller/processor 375implements layer 3 and layer 2 functionality. Layer 3 includes a radioresource control (RRC) layer, and layer 2 includes a service dataadaptation protocol (SDAP) layer, a packet data convergence protocol(PDCP) layer, a radio link control (RLC) layer, and a medium accesscontrol (MAC) layer. The controller/processor 375 provides RRC layerfunctionality associated with broadcasting of system information (e.g.,MIB, SIBs), RRC connection control (e.g., RRC connection paging, RRCconnection establishment, RRC connection modification, and RRCconnection release), inter radio access technology (RAT) mobility, andmeasurement configuration for UE measurement reporting; PDCP layerfunctionality associated with header compression/decompression, security(ciphering, deciphering, integrity protection, integrity verification),and handover support functions; RLC layer functionality associated withthe transfer of upper layer packet data units (PDUs), error correctionthrough ARQ, concatenation, segmentation, and reassembly of RLC servicedata units (SDUs), re-segmentation of RLC data PDUs, and reordering ofRLC data PDUs; and MAC layer functionality associated with mappingbetween logical channels and transport channels, multiplexing of MACSDUs onto transport blocks (TBs), demultiplexing of MAC SDUs from TBs,scheduling information reporting, error correction through HARQ,priority handling, and logical channel prioritization.

The transmit (TX) processor 316 and the receive (RX) processor 370implement layer 1 functionality associated with various signalprocessing functions. Layer 1, which includes a physical (PHY) layer,may include error detection on the transport channels, forward errorcorrection (FEC) coding/decoding of the transport channels,interleaving, rate matching, mapping onto physical channels,modulation/demodulation of physical channels, and MIMO antennaprocessing. The TX processor 316 handles mapping to signalconstellations based on various modulation schemes (e.g., binaryphase-shift keying (BPSK), quadrature phase-shift keying (QPSK),M-phase-shift keying (M-PSK), M-quadrature amplitude modulation(M-QAM)). The coded and modulated symbols may then be split intoparallel streams. Each stream may then be mapped to an OFDM subcarrier,multiplexed with a reference signal (e.g., pilot) in the time and/orfrequency domain, and then combined together using an Inverse FastFourier Transform (IFFT) to produce a physical channel carrying a timedomain OFDM symbol stream. The OFDM stream is spatially precoded toproduce multiple spatial streams. Channel estimates from a channelestimator 374 may be used to determine the coding and modulation scheme,as well as for spatial processing. The channel estimate may be derivedfrom a reference signal and/or channel condition feedback transmitted bythe UE 350. Each spatial stream may then be provided to a differentantenna 320 via a separate transmitter 318 TX. Each transmitter 318 TXmay modulate a radio frequency (RF) carrier with a respective spatialstream for transmission.

At the UE 350, each receiver 354 RX receives a signal through itsrespective antenna 352. Each receiver 354 RX recovers informationmodulated onto an RF carrier and provides the information to the receive(RX) processor 356. The TX processor 368 and the RX processor 356implement layer 1 functionality associated with various signalprocessing functions. The RX processor 356 may perform spatialprocessing on the information to recover any spatial streams destinedfor the UE 350. If multiple spatial streams are destined for the UE 350,they may be combined by the RX processor 356 into a single OFDM symbolstream. The RX processor 356 then converts the OFDM symbol stream fromthe time-domain to the frequency domain using a Fast Fourier Transform(FFT). The frequency domain signal comprises a separate OFDM symbolstream for each subcarrier of the OFDM signal. The symbols on eachsubcarrier, and the reference signal, are recovered and demodulated bydetermining the most likely signal constellation points transmitted bythe base station 310. These soft decisions may be based on channelestimates computed by the channel estimator 358. The soft decisions arethen decoded and deinterleaved to recover the data and control signalsthat were originally transmitted by the base station 310 on the physicalchannel. The data and control signals are then provided to thecontroller/processor 359, which implements layer 3 and layer 2functionality.

The controller/processor 359 can be associated with a memory 360 thatstores program codes and data. The memory 360 may be referred to as acomputer-readable medium. In the UL, the controller/processor 359provides demultiplexing between transport and logical channels, packetreassembly, deciphering, header decompression, and control signalprocessing to recover IP packets from the EPC 160. Thecontroller/processor 359 is also responsible for error detection usingan ACK and/or NACK protocol to support HARQ operations.

Similar to the functionality described in connection with the DLtransmission by the base station 310, the controller/processor 359provides RRC layer functionality associated with system information(e.g., MIB, SIBs) acquisition, RRC connections, and measurementreporting; PDCP layer functionality associated with headercompression/decompression, and security (ciphering, deciphering,integrity protection, integrity verification); RLC layer functionalityassociated with the transfer of upper layer PDUs, error correctionthrough ARQ, concatenation, segmentation, and reassembly of RLC SDUs,re-segmentation of RLC data PDUs, and reordering of RLC data PDUs; andMAC layer functionality associated with mapping between logical channelsand transport channels, multiplexing of MAC SDUs onto TBs,demultiplexing of MAC SDUs from TBs, scheduling information reporting,error correction through HARQ, priority handling, and logical channelprioritization.

Channel estimates derived by a channel estimator 358 from a referencesignal or feedback transmitted by the base station 310 may be used bythe TX processor 368 to select the appropriate coding and modulationschemes, and to facilitate spatial processing. The spatial streamsgenerated by the TX processor 368 may be provided to different antenna352 via separate transmitters 354TX. Each transmitter 354TX may modulatean RF carrier with a respective spatial stream for transmission.

The UL transmission is processed at the base station 310 in a mannersimilar to that described in connection with the receiver function atthe UE 350. Each receiver 318RX receives a signal through its respectiveantenna 320. Each receiver 318RX recovers information modulated onto anRF carrier and provides the information to a RX processor 370.

The controller/processor 375 can be associated with a memory 376 thatstores program codes and data. The memory 376 may be referred to as acomputer-readable medium. In the UL, the controller/processor 375provides demultiplexing between transport and logical channels, packetreassembly, deciphering, header decompression, control signal processingto recover IP packets from the UE 350. IP packets from thecontroller/processor 375 may be provided to the EPC 160. Thecontroller/processor 375 is also responsible for error detection usingan ACK and/or NACK protocol to support HARQ operations.

At least one of the TX processor 368, the RX processor 356, and thecontroller/processor 359 may be configured to perform aspects inconnection with group handover message component 199 of FIG. 1.

At least one of the TX processor 316, the RX processor 370, and thecontroller/processor 375 may be configured to perform aspects inconnection with group handover component 198 of FIG. 1.

As illustrated in FIG. 1, a wireless communication system may integrateone or more satellite 121 to facilitate the communication between a basestation and a UE. For example, a transparent satellite may relaycommunication transmitted from a base station to UEs to extend thecoverage of the base station to UEs outside of a transmission range ofthe base station. The satellite may perform amplification, spatialfiltering, or frequency conversion when relaying communication betweenthe base station and the UE. A link between the base station serving theUE and the satellite may be referred to as a feeder link. When atransparent satellite moves, it may need to switch the feeder linkbecause the base station associated with the feeder link is no longer inthe coverage of the satellite. Therefore, UEs served by the satellitemay need to be handed over to another base station (which may bereferred to as a target base station and the prior base station may bereferred to as a source base station). A handover mechanism thatindividually hands over each UE by transmitting a dedicated handovermessage (e.g., command) to each UE may be inefficient and would involvesending handover messages to the entire group of UEs served by thesource base station via the satellite. Additionally, each UE in thegroup of UEs attempting to connect to the target base station usingindividually stored handover messages may lead to congestion at thetarget base station. If each UE in the group of UEs does not store thehandover message and instead relies on the currently serving basestation (which may be referred as a source base station) to transmit thehandover messages, the separate handover message for each UE in thegroup of UEs increase system overhead.

FIGS. 4A and 4B illustrate example wireless communication environments400 and 450 with a satellite. As illustrated in FIG. 4A, a satellite 402may be an intermediary for communication between a base station 404A anda group of UEs 408 including one or more UEs 406A, 406B, 406C, and 406D.Four UEs are shown for illustrative purpose. The base station 404A maytransmit a signal encoding data, such as user data or control data forany UE in the group of UEs 408, to the satellite 402. The satellite 402may relay the data, such as by performing amplification, spatialfiltering, or frequency conversion, to one or more UEs in the group ofUEs 408. Any UE in the group of UEs 408 may communicate with the basestation 404A by transmitting a signal encoding data, such as user dataof the UE, to the satellite 402. The satellite 402 may then relay thedata, such as by performing amplification, spatial filtering, orfrequency conversion, to the base station 404A. The communication (i.e.,radio link) between the base station 404A and the satellite 402 may bereferred to as a feeder link A. In some aspects, the satellite 402 is atransparent satellite that is configured to perform amplification,spatial filtering, or frequency conversion. In some aspects, thesatellite 402 is a regenerative satellite that may additionally performother signal processing for relaying such as decoding, interferencecancellation, signal regeneration but does not have the fullfunctionality of a base station.

As illustrated in FIG. 4B, as the satellite 402 moves (e.g., by orbitingaround the Earth), the satellite 402 may move out of a coverage area ortransmission range of the base station 404A. Therefore, the base station404A may handover the group of UEs 408 to another base station 404B thatwould have the satellite 402 in its coverage area. The satellite 402 mayswitch the feeder link from base station 404A to base station 404B. Thebase station 404A and the base station 404B may be connected at 410 witheach other via a core network, such as core network 190 or EPC 160 shownin FIG. 1. The base station 404A may transmit a handover request to thebase station 404B and the base station 404B may acknowledge the handoverrequest. The handover request may request to handover the group of UEsto the base station 404B. To signal the handover to the group of UEs408, the base station 404A may transmit a group handover message 412 tothe group of UEs 408. The group handover message 412 may be transmittedto the group of UEs 408 from the base station 404A via the satellite402. The group of UEs 408 may establish a connection with the basestation 404B via the satellite 402 based on the group handover message.Because the group of UEs 408 established connection with the basestation 404B, the satellite 402 switched the feeder link from basestation 404A to base station 404B.

FIG. 5 is an example communication flow 500 between a group of UEs and abase station that communicates via a satellite. As illustrated in FIG.5, a group of UEs 502 including one or more UEs 502A, 502B, and 502N arein communication 510 with a base station 504A via a satellite 506. TheUEs 502A-502N may have an RRC connection with the base station 504A, forexample. In some aspects, communication 510 between the base station504A and the UEs in the group of UEs 502 may be exchanged via thesatellite 506. The communication 510 may include data, control, etc. Thecommunication 510 may include downlink communication and/or uplinkcommunication.

The base station 504A may transmit a signal encoding data, such as userdata or control data for any UE in the group of UEs 502, to thesatellite 506. The satellite 506 may relay the data, such as byperforming amplification, spatial filtering, or frequency conversion, toone or more UEs in the group of UEs 502. A UE in the group of UEs 502may communicate with the base station 504A by transmitting a signalencoding data, such as user data of the UE, to the satellite 506. Thesatellite 506 may then relay the data, such as by performingamplification, spatial filtering, or frequency conversion, to the basestation 504A. The communication link (i.e., radio link) between the basestation 504A and the satellite 506 may be referred to as a feeder linkA. In some aspects, the satellite 506 is a transparent satellite that isconfigured to perform amplification, spatial filtering, or frequencyconversion. In some aspects, the satellite 506 is a regenerativesatellite that may additionally perform other signal processing forrelaying such as decoding, interference cancellation, signalregeneration but does not have the full functionality of a base station.

The satellite 506 may move (such as by orbiting around the Earth). Asthe satellite 506 moves at 512, the satellite may move out of a coveragearea of the base station 504A. In some aspects, the UEs in the group ofUE 502 may determine the occurrence of a trigger event 514 based on anyof a variety of parameters such as 1) measurement events related to cellquality or propagation delay (e.g., when a measured quality is below athreshold or a delay is above a threshold), 2) location of the UEs andthe satellite, 3) one or more timers that are configured in accordancewith serve time and expected movement of the satellite, or 4) elevationangles of source and target cells. The UEs in the group of UEs 502 mayreport the occurrence of the event 516 (e.g., the measurement events) tothe base station 504A. In some examples, the occurrence of the event maybe determined at the base station, e.g., based on measurementinformation from one or more of the UEs in the group of UEs 502, one ormore timers, a location of the satellite or the UEs, etc. The basestation 504A may determine to initiate a group handover for the group ofUEs 502. The base station 504A may determine, at 518, to initiate agroup handover for the group of UEs 502. The determination may be basedon any of a variety of triggering events. For example, the base station504A may determine to initiate the group handover based onmeasurement-based triggering where cell quality for the group of UEs 502has exceeded or fallen below a configured threshold. Alternatively oradditionally, the base station 504A may determine to initiate the grouphandover based on locations of the group of UEs 502 and/or a location ofthe satellite 506. Alternatively or additionally, the base station 504Amay determine to initiate the group handover based on additionaltriggering conditions based on timing advance value to the target cell.Alternatively or additionally, the base station 504A may determine toinitiate the group handover based on elevation angles of source andtarget cells. The base station 504A may determine to initiate the grouphandover based on measurements from the group of UEs 502 or independentof the measurements performed by the group of UEs 502.

After the base station 504A determines, at 518, to handover the group ofUEs 502, the base station 504A may transmit a handover request 520 tothe base station 504B and receive a handover acknowledgment 522 from thebase station 504B. Then the base station 504A may transmit one or moregroup handover messages 524 to the group of UEs 502. Each UE in thegroup of UEs processes the group handover message 524, as illustrated at525, in order to determine that the UE is being handed over to a targetbase station.

In some aspects, as part of the handover acknowledgment 522 or the grouphand over messages 524, the base station 504A may transmit an RRCreconfiguration with synchronization message in a PDSCH that includesgroup handover messages, or group handover commands, to the group of UEs502. A cell specific common search space may be configured, and thegroup of UEs 502 may monitor the cell specific common search space toreceive the PDSCH indicating the HO command for the group of UEs. Thegroup handover command may include bits that are scrambled based on acell specific group radio network temporary identifier (RNTI). Signalingradio bearer 1 (SRB1) information may provide a UE specificconfiguration, and UE specific integrity protection and ciphering of theRRC message may be applied for the SRB1 information for each individualUE in the group. An SRB-x, such as SRB 3 or SRB 4, may include groupspecific configuration information and may be protected with securityinformation that is known to each of the UEs in the group. For example,access stratum (AS) security information may be transmitted to the groupof UEs 502, and the signaling radio bearer information may be sent tothe group of UEs with integrity protection and ciphering based on the ASsecurity information for the group of UEs. A common group AS key may beprovided to each UE in the group of UEs 502 upon joining of the group.In some aspects, the common group AS key may be derived using a set ofcell specific or group specific parameters. For the group handover, thebase station may transmit an RRC message that includes a list of RRCreconfiguration messages for multiple UEs. The RRC reconfigurationmessages may include delta RRC configuration for each UE based on theparticular UE's current configuration. A delta RRC configuration mayrefer to a configuration that includes parameters that are differentthan the UE's current configuration without including parameters thatare the same as the UE's current configuration. In some aspects, one ormore UE in the group of UEs 502 may not be provided with an RRCreconfiguration by the base station. The UE may interpret the absence ofan RRC reconfiguration, or an RRC reconfiguration delta, as anindication to continue to use the UE's current RRC configuration withthe target base station. In such aspects, a UE in the group of UEs 502may continue to 526 to initiate an RRC connection with the target basestation 504B using their respective current RRC configuration. The UEsin the group of UEs 502 may receive a response from the base station504B at 528 and may transmit an RRC reconfiguration completionindication at 530. At 532, the UEs in the group of UEs 502 may transmitor receive user data with the target base station 504B. In some aspects,the communication (e.g., data 532) between the base station 504B and theUEs in the group of UEs 502 may be exchanged via the satellite 506.

In some aspects, the base station 504A may transmit the group handovermessage 524 comprising multiple RRC messages to the group of UEs 502.The multiple RRC messages may be multiplexed at medium access control(MAC) using one or more same or different logical channel identifiers(LCIDs). Each UE in the group of UEs 502 may attempt to decode all ofthe RRC messages in the multiplexed RRC messages (such as in SRB1). Insome aspects, each UE may utilize a current SRB1 configuration and ASsecurity profile for the particular UE to attempt to decode the multipleRRC messages. A UE in the group of UEs may decode a single RRC messagefrom the multiplexed RRC messages based on the UE's AS security profile,e.g., one RRC message will pass the integrity protection check for theUE. In some aspects, each UE may use a default SRB1 configuration. Afterdecoding the RRC messages, the UEs in the group of UEs 502 may initiateRRC reconfiguration with the target base station 504B. The UEs in thegroup of UEs 502 may receive a response 528 from the base station 504Band may transmit an RRC reconfiguration completion indication 530. Afterestablishing the connection with the target base station, the UEs in thegroup of UEs 502 may transmit or receive user data 532 with the targetbase station 504B.

Each UE may be able to decode one RRC message intended for the UE andmay fail to decode the other RRC messages that are not intended for theUE because the other RRC messages will fail an integrity protectioncheck and may be subsequently discarded. Each RRC reconfiguration mayinclude a delta configuration based on default UE configuration for thetarget. The delta configuration may refer to a configuration thatincludes parameters that are different than the default configurationwithout including parameters that are the same as the defaultconfiguration. The size of the group (e.g., the number of UEs in thegroup of UEs 502) may be configured by a network to fit the grouphandover message in a single transport block signal (TBS) size. Forexample, the number of UEs in the group of UEs may be based on an amountof group handover information that can be transmitted in one or moreTBSs, e.g., in a single TBS.

In some aspects, the group handover message 524 may be transmitted in abroadcast or a groupcast message that is received by the group of UEs.In some aspects, the broadcast or groupcast message may be protectedusing common security keys for the group of UEs 502. The common securitykeys may be provided to the group of UEs 502 using dedicated RRCsignaling. In some aspects, based on time and/or location, each UE inthe group of UEs 502 may check the broadcast or groupcast message todetermine if the group handover message 524 is provided for a targetcell of the target base station 504B. In some aspects, the base station504A may transmit (e.g., in communication 510) a group specific or UEspecific indication to each UE in the group of UEs 502 to check thebroadcast or groupcast message to schedule the time for the grouphandover message 524 to be transmitted as a broadcast message. In someaspects, the scheduling information may be provided to the group of UEsin the group handover message. In some aspects, the schedulinginformation may be provided to the group of UEs using an RRCreconfiguration upon a UE moving to RRC connected state or may bebroadcast in system information, such as a SIB1. In some aspects, eachUE in the group of UEs 502 may acquires the broadcast or groupcast PDSCHbefore accessing the target cell at 526. The broadcast or groupcastmessage may be protected using common security keys for the group ofUEs. The common security keys may be provided to the group of UEs indedicated signaling for the group of UEs or to each UE in the group ofUEs. If no group handover message is configured or received, each UE inthe group of UEs 502 can initiate RRC re-establishment procedure at 526,such as based on preconfigured time/location. The UEs in the group ofUEs 502 may receive a response 528 from the base station 504B and maytransmit an RRC reconfiguration completion indication 530. Then, the UEsin the group of UEs 502 may transmit or receive user data 532 with thetarget base station 504B.

The RRC reconfigurations may include delta configurations. The deltaconfiguration may be based on each UE's source configuration or currentconfiguration. The delta configuration may indicate parameters of theconfiguration that are different than the UE's source configuration or adefault configuration without indicating parameters that will remainunchanged. In some aspects, the delta configuration for each UE in thegroup of UEs 502 may be based on a default UE configuration for thetarget base station 504B. The default UE configuration for the targetbase station 504B may be a full configuration of parameters forcommunication with the target base station. In some aspects, the defaultUE configuration for the target base station 504B may be provided beforethe handover decision at 518. In some aspects, the group handovermessage may provide common target configuration for each UE in the groupof UEs. A list of RRC reconfigurations may include delta configurationthat individually indicate one or more parameters that will be changedfor each UE.

In some aspects, the group handover message may include an indication tocontinue to use a current source cell configuration. In some aspects,the target base station 504B may accept the same UE radio configurationthat was used in the source base station 504A. The cell specific/carrierspecific configuration for the UEs may be the same. Security keys may bedifferent between the source base station and the target base station,and the UEs may receive a next hop chaining counter (NCC) and/or a cellradio network temporary identifier (C-RNTI) for the target base stationin the group handover message.

A new feeder link to a new base station may lead to a different timedelay for communication. In some aspects, the group handover message mayinclude a new round trip delay (RTD) value between satellite and gateway(i.e., the target base station 504B). The new RTD value may be used byeach UE in the group of UEs 502 for uplink pre-compensation, such as inuplink transmissions in 526, 530, and 532. The new RTD value may beincluded in a system information block (SIB).

In some aspects, if timing advance (TA) would be different for thetarget base station 504B compared with the base station 504A, the basestation 504A may provide adjustment to TA using UE specific or groupspecific indication (e.g., DCI using group RNTI) to adjust the feederlink propagation delay which is common to each UE in the group of UEs inthe group of UEs 502. The pre-compensation applied to the UE tosatellite link may remain the same. The UEs in the group of UEs 502 mayuse the same TA for the target base station 504B without receiving anindication of TA adjustment. In some aspects, the UEs in the group ofUEs 502 may read system information to receive the latest commonconfiguration that may include paging, random access and initialpre-compensation TA values for initial access before initiating the RRCaccess with base station 504B at 526. In such aspects, the grouphandover message may not include common configuration or systeminformation to reduce the size of the handover message and the UEs inthe group of UEs 502 may initiate the RRC access with base station 504Bat 526 based on pre-configured execution condition, such as time,location, or the like.

In some aspects, SIB in the cell is considered not changed after thefeeder link changes from base station 504A to base station 504B. Theinformation regarding SIB may be transparent to UEs in IDLE mode or RRCINACTIVE mode. For such UEs, changes in RTD may not trigger SI updatingprocedure.

FIG. 6 is a flowchart 600 of a method of wireless communication. Themethod may be performed by a base station (e.g., the base station102/180; the base station 310; the base station 504A, the base station404A, the apparatus 802). The method helps to provide a more efficienthandover of a group of UEs and to reduce signaling overhead to hand eachof the UEs over to a target base station.

At 604, the base station transmits a group handover request for thegroup of UEs to a target base station. For example, the base station504A may transmit handover request 520 to the target base station 504B.For example, transmission 604 may be performed by group handover requestcomponent 842. Transmission 604 may include aspects described inconjunction with handover request 520 of FIG. 5. In some aspects, thebase station transmits the group handover request to check with thetarget base station regarding whether the target base station has theresources to process the handover.

At 606, the base station receives a group handover acknowledgment fromthe target base station. For example, the base station 504A may receivehandover acknowledgment 522 from the base station 504B. For example,reception 606 may be performed by reception component 830. Reception 606may include aspects described in conjunction with handoveracknowledgment 522 of FIG. 5. In some aspects, the target base stationmay transmit the handover acknowledgment to indicate that the targetbase station can be used as target for handover.

At 608, the base station transmits a group handover message to the groupof UEs. For example, transmission 608 may be performed by transmissioncomponent 834. For example, the base station 504A may transmit a grouphandover message 524 to the group of UEs 502. In some aspects, the grouphandover message is transmitted to each UE in the group of UEs in an RRCreconfiguration with synchronization. In some aspects, the grouphandover message is transmitted to the group of UEs based on a cellspecific common search space. In some aspects, at least a portion of thegroup handover message is scrambled with a cell specific group RNTI. Insome aspects, the RRC reconfiguration comprises an RRC messagecomprising a list of RRC reconfiguration messages for each UE in thegroup of UEs. In some aspects, an RRC reconfiguration message in thelist of RRC reconfiguration messages indicates a difference with respectto a current configuration for a respective UE.

FIG. 7 is a flowchart 700 of a method of wireless communication. Themethod may be performed by a base station (e.g., the base station102/180; the base station 310; the base station 504A, the base station404A, the apparatus 802). The method helps to provide a more efficienthandover of a group of UEs and to reduce signaling overhead to hand eachof the UEs over to a target base station.

In some aspects, at 701, the base station provides a common AS key andgroup specific or default signaling radio bearer configuration to agroup of UEs. For example, the base station 504A may provide common ASkey and group specific or default signaling radio bearer configurationto a group of UEs. In some aspects, the base station sends new SRBinformation to the group of UEs with integrity protection and cipheringbased on the common AS key and group specific new SRB configuration. Insome aspects, provision 701 may be performed by AS Key and configurationcomponent 848.

At 702, the base station determines to perform a group handover for thegroup of UEs. For example, determination 702 may be performed bydetermination component 840. For example, the base station 504A maydetermine to perform a group handover at 518. In some aspects, the basestation communicates with the group of UEs via a transparent satellite,such as the satellite 506/402. The base station may determine to performa group handover for the group of UEs based on a variety of triggersthat may be triggered due to movement of satellite. For example, thebase station may determine to perform the group handover based onmeasurement-based triggering where cell quality for the group of UEs hasvaried passed a preconfigured threshold. Alternatively or additionally,the base station may determine to perform the group handover based onlocation of the group of UEs and the satellite. Alternatively oradditionally, the base station may determine to perform the grouphandover based on additional triggering conditions based on timingadvance value to the target cell. Alternatively or additionally, thebase station may determine to perform the group handover based onelevation angles of source and target cells. The base station 504A maydetermine to perform the group handover based on or independent of themeasurements performed by the group of UEs.

At 704, the base station transmits a group handover request for thegroup of UEs to a target base station. For example, the base station504A may transmit handover request 520 to the target base station 504B.For example, transmission 704 may be performed by group handover requestcomponent 842. Transmission 704 may include aspects described inconjunction with handover request 520 of FIG. 5. In some aspects, thebase station transmits the group handover request to check with thetarget base station regarding whether the target base station has theresources to process the handover.

At 706, the base station receives a group handover acknowledgment fromthe target base station. For example, the base station 504A may receivehandover acknowledgment 522 from the base station 504B. For example,reception 706 may be performed by reception component 830. Reception 706may include aspects described in conjunction with handoveracknowledgment 522 of FIG. 5. In some aspects, the target base stationmay transmit the handover acknowledgment to indicate that the targetbase station can be used as target for handover.

In some aspects, at 707, the base station provides configurationinformation for each UE in the group of UEs. For example, the basestation 504A may provide configuration information for each UE in thegroup of UEs 502. For example, provision 707 may be performed by AS Keyand configuration component 848. The configuration information for eachUE in the group of UEs may indicate a change in one or moreconfiguration parameters for the UE relative to a common configurationfor the target base station. In some aspects, the common configurationincludes a default configuration for the target base station applicableto all UEs (each UE in the group of UEs) or a full configuration for thetarget base station. In some aspects, the configuration information isprovided to the group of UEs in the group handover message or in adownlink message prior to the handover decision. In some aspects,provision 707 may be part of transmission 708 or may occur prior todetermination 702.

At 708, the base station transmits a group handover message to the groupof UEs. For example, transmission 708 may be performed by transmissioncomponent 834. For example, the base station 504A may transmit a grouphandover message 524 to the group of UEs 502. In some aspects, the grouphandover message is transmitted to each UE in the group of UEs in an RRCreconfiguration with synchronization. In some aspects, the grouphandover message is transmitted to the group of UEs based on a cellspecific common search space. In some aspects, at least a portion of thegroup handover message is scrambled with a cell specific group RNTI. Insome aspects, the RRC reconfiguration comprises an RRC messagecomprising a list of RRC reconfiguration messages for each UE in thegroup of UEs. In some aspects, an RRC reconfiguration message in thelist of RRC reconfiguration messages indicates a difference with respectto a current configuration for a respective UE.

In some aspects, the group handover message comprises a MAC messagecomprising multiplexed radio resource control RRC messages using one ormore logical channel identifiers LCIDs. In some aspects, each RRCmessage in the multiplexed RRC messages is based on a SRB configurationand AS key for a UE in the group of UEs. In some aspects, the SRBconfiguration is specific to the UE or comprises a default radio bearerconfiguration. In some aspects, each RRC message in the multiplexed RRCmessages includes a delta configuration based on default UEconfiguration for the target base station. In some aspects, a size ofthe group of UEs is based on an amount of the multiplexed RRC messagesallowed in a single TBS.

In some aspects, the group handover message is transmitted in agroupcast message. The groupcast message may be transmitted at aspecified or pre-defined time or location for the group of UEs. The basestation may transmit an indication to one or more UEs of the group ofUEs when to check the groupcast message. In some aspects, the groupcastmessage comprises scheduling information. In some aspects, the groupcastmessage is encrypted using a group common security key for the group ofUEs.

In some aspects, the handover message comprises an indication tocontinue to use a current source cell configuration with the target basestation. The handover message may comprise a new security key forcommunication with the target base station. In some aspects, thehandover message comprises an NCC and a C-RNTI for the target basestation. In some aspects, the handover message comprises a new RTD valuefor the target base station. In some aspects, the handover messagecomprises a new TA for the target base station.

FIG. 8 is a diagram 800 illustrating an example of a hardwareimplementation for an apparatus 802. The apparatus 802 is a BS andincludes a baseband unit 804. The baseband unit 804 may communicatethrough a cellular RF transceiver with the UE 104. The baseband unit 804may include a computer-readable medium/memory. The baseband unit 804 isresponsible for general processing, including the execution of softwarestored on the computer-readable medium/memory. The software, whenexecuted by the baseband unit 804, causes the baseband unit 804 toperform the various functions described supra. The computer-readablemedium/memory may also be used for storing data that is manipulated bythe baseband unit 804 when executing software. The baseband unit 804further includes a reception component 830, a communication manager 832,and a transmission component 834. The communication manager 832 includesthe one or more illustrated components. The components within thecommunication manager 832 may be stored in the computer-readablemedium/memory and/or configured as hardware within the baseband unit804. The baseband unit 804 may be a component of the BS 310 and mayinclude the memory 376 and/or at least one of the TX processor 316, theRX processor 370, and the controller/processor 375.

The communication manager 832 includes a determination component 840that is configured to determine to perform group handover for a group ofUEs, e.g., as described in connection with determination 702 of FIG. 7.

The communication manager 832 includes a group handover requestcomponent 842 that transmits a group handover request for the group ofUEs to a target base station, e.g., as described in connection withtransmission 604 of FIG. 6 and transmission 704 of FIG. 7.

The communication manager 832 includes a group handover acknowledgmentcomponent 844 that receives a group handover acknowledgment from thetarget base station, e.g., as described in connection with reception 606of FIG. 6 and reception 706 of FIG. 6.

The communication manager 832 includes a group handover messagecomponent 846 that transmits a group handover message to the group ofUEs, e.g., as described in connection with transmission 608 of FIG. 6and transmission 708 of FIG. 7.

The communication manager 832 includes a AS Key and configurationcomponent 848 that provides configuration information for each UE in thegroup of UEs and provides a common AS key and group specific or defaultsignaling radio bearer configuration to the group of UEs, e.g., asdescribed in connection with provisions 701 and 707 of FIG. 7.

The apparatus may include additional components that perform each of theblocks of the algorithm in the aforementioned flowcharts of FIGS. 6 and7. As such, each block in the aforementioned flowcharts of FIGS. 6 and 7may be performed by a component and the apparatus may include one ormore of those components. The components may be one or more hardwarecomponents specifically configured to carry out the statedprocesses/algorithm, implemented by a processor configured to performthe stated processes/algorithm, stored within a computer-readable mediumfor implementation by a processor, or some combination thereof.

In one configuration, the apparatus 802, and in particular the basebandunit 804, includes means for determining to perform group handover for agroup of UEs. The baseband unit 804 may further include means fortransmitting a group handover request for the group of UEs to a targetbase station. The baseband unit 804 may further include means forreceiving a group handover acknowledgment from the target base station.The baseband unit 804 may further include means for transmitting a grouphandover message to the group of UEs. The aforementioned means may beone or more of the aforementioned components of the apparatus 802configured to perform the functions recited by the aforementioned means.As described supra, the apparatus 802 may include the TX Processor 316,the RX Processor 370, and the controller/processor 375. As such, in oneconfiguration, the aforementioned means may be the TX Processor 316, theRX Processor 370, and the controller/processor 375 configured to performthe functions recited by the aforementioned means.

FIG. 9 is a flowchart 900 of a method of wireless communication. Themethod may be performed by a UE (e.g., the UE 94; a UE in the group ofUEs 408; a UE in the group of UEs 502; the apparatus 802) served by asource base station. In some aspects, a size of the group of UEs isbased on an amount of RRC messages allowed in a single TBS. The methodhelps to provide a more efficient handover of a group of UEs and toreduce signaling overhead to hand each of the UEs over to a target basestation.

At 908, the UE may receive a group handover message comprising RRCconfiguration for one or more UEs transmitted to a group of UEscomprising the one or more UEs from the source base station. Forexample, a UE in the UEs 502 may receive the group handover message 524from the base station 504A. For example, reception 908 may be performedby group handover message reception component 1140. In some aspects, thesource base station communicates with the group of UEs via a satellite.In some aspects, the group handover message is received in an RRCreconfiguration with synchronization for the group of UEs. In someaspects, the UE receives the group handover message in a cell specificcommon search space. In some aspects, at least a portion of the grouphandover message is scrambled with a cell specific group RNTI.

At 910, the UE connects to a target base station using the RRCconfiguration based on the group handover message. For example, a UE inthe UEs 502 may establish connection with the base station 504B based onthe group handover message. For example, connection 910 may be performedby group handover connection component 1142. To connect to the targetbase station, in some aspects, the UE decodes one RRC message in themultiplexed RRC messages that is directed to the UE.

FIG. 10 is a flowchart 1000 of a method of wireless communication. Themethod may be performed by a UE (e.g., the UE 104; a UE in the group ofUEs 408; a UE in the group of UEs 502; the apparatus 802) served by asource base station. In some aspects, a size of the group of UEs isbased on an amount of RRC messages allowed in a single TBS. The methodhelps to provide a more efficient handover of a group of UEs and toreduce signaling overhead to hand each of the UEs over to a target basestation.

At 1006, the UE receives, from the source base station, a common AS keyand a group specific or default SRB configuration that is common to thegroup of UEs. For example, a UE in the UEs 502 may receive a common ASkey and a group specific or default SRB configuration from the basestation 504A. For example, reception 1006 may be performed by AS keycomponent 1148. In some aspects, new SRB information in the grouphandover message includes integrity protection and cyphering based onthe common AS key and group specific new SRB configuration.

At 1008, the UE receives a group handover message comprising RRCconfiguration for one or more UEs transmitted to a group of UEscomprising the one or more UEs from the source base station. Forexample, a UE in the UEs 502 may receive the group handover message 524from the base station 504A. For example, reception 1008 may be performedby group handover message reception component 1140. In some aspects, thesource base station communicates with the group of UEs via a satellite.In some aspects, the group handover message is received in an RRCreconfiguration with synchronization for the group of UEs. In someaspects, the UE receives the group handover message in a cell specificcommon search space. In some aspects, at least a portion of the grouphandover message is scrambled with a cell specific group RNTI.

In some aspects, the RRC reconfiguration comprises an RRC messagecomprising a list of RRC reconfiguration messages for each UE in thegroup of UEs. In some aspects, an RRC reconfiguration message in thelist of RRC reconfiguration messages that is for the UE indicates one ormore different parameters with respect to a current configuration forthe UE. In some aspects, the group handover message comprises a MACmessage including multiplexed RRC messages using one or more LCIDs.

In some aspects, the UE receives the group handover message in agroupcast message. As part of 1008, at 1009, the UE may check thegroupcast message for the group handover message based on a specified orpre-defined time or a location and may receive an indication from thesource base station about the groupcast message. The UE may receive thegroup handover message in the groupcast message in response to receivingthe indication. The indication may be specific to the UE or may be forthe group of UEs. In some aspects, UE acquires the groupcast message ina PDSCH before accessing a target cell of a target base station.

In some aspects, the groupcast message comprises scheduling information.In some aspects, the groupcast message is encrypted using a group commonsecurity key provided for the group of UEs. In some aspects, the grouphandover message comprises an indication to continue to use a currentsource cell configuration with the target base station. In some aspects,the group handover message comprises a new security key forcommunication with the target base station. In some aspects, the grouphandover message comprises an NCC and a C-RNTI for the target basestation. In some aspects, the group handover message comprises a new RTDvalue. In some aspects, the group handover message comprises a new TA.

In some aspects, system information comprising common configuration andpre-compensation value for the target base station may be included inthe group handover message. In some aspects, system informationcomprising common configuration and pre-compensation value for thetarget base station are not included in the group handover message. Insuch aspects, the UE may receive system information comprising commonconfiguration and pre-compensation value for the target base station at1002 before connecting to the target base station. In some aspects, thecommon configuration for the target base station comprises a defaultconfiguration for the target base station applicable to each UE in thegroup of UEs or full configuration for the target base station. In someaspects, the configuration information is received in the group handovermessage or in a downlink message prior to the handover decision. In someaspects, at 1004, the UE may receive configuration information from thesource base station that indicates a change in one or more configurationparameters for the UE relative to a common configuration for the targetbase station.

At 1010, the UE connects to a target base station using the RRCconfiguration based on the group handover message. For example, a UE inthe UEs 502 may establish connection with the base station 504B based onthe group handover message. For example, connection 1010 may beperformed by group handover connection component 1142. To connect to thetarget base station, in some aspects, the UE decodes one RRC message inthe multiplexed RRC messages that is directed to the UE. In someaspects, the UE uses a current UE specific SRB 1 and AS securitykey/profile received at reception 1006 to attempt to decode themultiplexed RRC messages to determine the RRC message intended for it.In some aspects, the UE uses a default SRB1, such as a SRB1 received atreception 1002 or 1006 to attempt to decode the multiplexed messages. Insome aspects, the UE may be able to decode the RRC message intended forthe UE and may fail to decode the other RRC messages.

In some aspects, one RRC message that is directed to the UE from themultiplexed RRC messages includes a delta configuration based on defaultUE configuration for the target base station.

In some aspects, the group handover message is transmitted in asynchronization message transmitted to each UE in the group of UEs in anRRC reconfiguration.

In some aspects, each UE in the group of UEs is configured with a cellspecific group RNTI. In some aspects, the RRC reconfiguration comprisesan RRC message comprising a list of RRC reconfiguration messages foreach UE in the group of UEs. In some aspects, each UE in the group ofUEs receives a common AS key and a group specific configuration. In someaspects, each UE in the group of UEs is configured with a UE specificSRB1.

In some aspects, the group handover message is transmitted in multipleRRC messages multiplexed at MAC using one or more LCIDs or cell radionetwork temporary identifiers (C-RNTIs) MAC control elements.

FIG. 11 is a diagram 1100 illustrating an example of a hardwareimplementation for an apparatus 1102. The apparatus 1102 is a UE andincludes a cellular baseband processor 1104 (also referred to as amodem) coupled to a cellular RF transceiver 1122 and one or moresubscriber identity modules (SIM) cards 1120, an application processor1106 coupled to a secure digital (SD) card 1108 and a screen 1110, aBluetooth module 1112, a wireless local area network (WLAN) module 1114,a Global Positioning System (GPS) module 1116, and a power supply 1118.The cellular baseband processor 1104 communicates through the cellularRF transceiver 1122 with the UE 104 and/or BS 102/180. The cellularbaseband processor 1104 may include a computer-readable medium/memory.The computer-readable medium/memory may be non-transitory. The cellularbaseband processor 1104 is responsible for general processing, includingthe execution of software stored on the computer-readable medium/memory.The software, when executed by the cellular baseband processor 1104,causes the cellular baseband processor 1104 to perform the variousfunctions described supra. The computer-readable medium/memory may alsobe used for storing data that is manipulated by the cellular basebandprocessor 1104 when executing software. The cellular baseband processor1104 further includes a reception component 1130, a communicationmanager 1132, and a transmission component 1134. The communicationmanager 1132 includes the one or more illustrated components. Thecomponents within the communication manager 1132 may be stored in thecomputer-readable medium/memory and/or configured as hardware within thecellular baseband processor 1104. The cellular baseband processor 1104may be a component of the UE 350 and may include the memory 360 and/orat least one of the TX processor 368, the RX processor 356, and thecontroller/processor 359. In one configuration, the apparatus 1102 maybe a modem chip and include just the baseband processor 1104, and inanother configuration, the apparatus 1102 may be the entire UE (e.g.,see 350 of FIG. 3) and include the aforediscussed additional modules ofthe apparatus 1102.

The communication manager 1132 includes a group handover messagereception component 1140 that is configured to receive a group handovermessage comprising RRC configuration for one or more UEs transmitted toa group of UEs comprising the one or more UEs from the source basestation, e.g., as described in connection with 908 in FIGS. 9 and 1008in FIG. 10.

The communication manager 1132 further includes a group handoverconnection component 1142 that is configured to connect to a target basestation using the RRC configuration based on the group handover message,e.g., as described in connection with 910 in FIGS. 9 and 1010 in FIG.10.

The communication manager 1132 may further include a SI receptioncomponent 1144 that is configured to receive system informationcomprising common configuration and pre-compensation value from a sourcebase station, e.g., as described in connection with 1002 in FIG. 10.

The communication manager 1132 may further include a SI change receptioncomponent 1146 that is configured to receive configuration informationfrom the source base station that indicates a change in one or moreconfiguration parameters for the UE relative to a common configurationfor the target base station, e.g., as described in connection with 1004in FIG. 10.

The communication manager 1132 may further include an AS key component1148 that is configured to receive a common AS key and a group specificor default SRB configuration from the source base station, e.g., asdescribed in connection with 1006 of FIG. 10.

The communication manager 1132 may further include an indicationreception component 1150 that is configured to check a groupcast messagefor the group handover message based on a specified or pre-defined timeor a location and receive an indication from the source base stationabout the groupcast message, e.g., as described in connection with 1009of FIG. 10.

The apparatus may include additional components that perform each of theblocks of the algorithm in the aforementioned flowcharts of FIGS. 9 and10. As such, each block in the aforementioned flowcharts of FIGS. 9 and10 may be performed by a component and the apparatus may include one ormore of those components. The components may be one or more hardwarecomponents specifically configured to carry out the statedprocesses/algorithm, implemented by a processor configured to performthe stated processes/algorithm, stored within a computer-readable mediumfor implementation by a processor, or some combination thereof.

In one configuration, the apparatus 1102, and in particular the cellularbaseband processor 1104, includes means for receiving a group handovermessage transmitted to a group of UEs from a source base station andmeans for connecting to a target base station based on the grouphandover message. The aforementioned means may be one or more of theaforementioned components of the apparatus 1102 configured to performthe functions recited by the aforementioned means. As described supra,the apparatus 1102 may include the TX Processor 368, the RX Processor356, and the controller/processor 359. As such, in one configuration,the aforementioned means may be the TX Processor 368, the RX Processor356, and the controller/processor 359 configured to perform thefunctions recited by the aforementioned means.

It is understood that the specific order or hierarchy of blocks in theprocesses/flowcharts disclosed is an illustration of example approaches.Based upon design preferences, it is understood that the specific orderor hierarchy of blocks in the processes/flowcharts may be rearranged.Further, some blocks may be combined or omitted. The accompanying methodclaims present elements of the various blocks in a sample order, and arenot meant to be limited to the specific order or hierarchy presented.

The previous description is provided to enable any person skilled in theart to practice the various aspects described herein. Variousmodifications to these aspects will be readily apparent to those skilledin the art, and the generic principles defined herein may be applied toother aspects. Thus, the claims are not intended to be limited to theaspects shown herein, but is to be accorded the full scope consistentwith the language claims, wherein reference to an element in thesingular is not intended to mean “one and only one” unless specificallyso stated, but rather “one or more.” Terms such as “if,” “when,” and“while” should be interpreted to mean “under the condition that” ratherthan imply an immediate temporal relationship or reaction. That is,these phrases, e.g., “when,” do not imply an immediate action inresponse to or during the occurrence of an action, but simply imply thatif a condition is met then an action will occur, but without requiring aspecific or immediate time constraint for the action to occur. The word“exemplary” is used herein to mean “serving as an example, instance, orillustration.” Any aspect described herein as “exemplary” is notnecessarily to be construed as preferred or advantageous over otheraspects. Unless specifically stated otherwise, the term “some” refers toone or more. Combinations such as “at least one of A, B, or C,” “one ormore of A, B, or C,” “at least one of A, B, and C,” “one or more of A,B, and C,” and “A, B, C, or any combination thereof” include anycombination of A, B, and/or C, and may include multiples of A, multiplesof B, or multiples of C. Specifically, combinations such as “at leastone of A, B, or C,” “one or more of A, B, or C,” “at least one of A, B,and C,” “one or more of A, B, and C,” and “A, B, C, or any combinationthereof” may be A only, B only, C only, A and B, A and C, B and C, or Aand B and C, where any such combinations may contain one or more memberor members of A, B, or C. All structural and functional equivalents tothe elements of the various aspects described throughout this disclosurethat are known or later come to be known to those of ordinary skill inthe art are expressly incorporated herein by reference and are intendedto be encompassed by the claims. Moreover, nothing disclosed herein isintended to be dedicated to the public regardless of whether suchdisclosure is explicitly recited in the claims. The words “module,”“mechanism,” “element,” “device,” and the like may not be a substitutefor the word “means.” As such, no claim element is to be construed as ameans plus function unless the element is expressly recited using thephrase “means for.”

The following examples are illustrative only and may be combined withaspects of other embodiments or teachings described herein, withoutlimitation.

Aspect 1 is an apparatus for wireless communication of a base station,comprising: a memory; and at least one processor coupled to the memoryand configured to: transmit a group handover request for a group of UEsto a target base station; receive a group handover acknowledgment fromthe target base station; and transmit a group handover message to thegroup of UEs.

Aspect 2 is the apparatus of aspect 1, wherein the base stationcommunicates with the group of UEs via a satellite, and wherein thegroup handover message is transmitted to each UE in the group of UEs ina RRC reconfiguration with synchronization.

Aspect 3 is the apparatus of any of aspects 1-2, wherein the grouphandover message is transmitted to the group of UEs based on a cellspecific common search space, and wherein at least a portion of thegroup handover message is scrambled with a cell specific group RNTI.

Aspect 4 is the apparatus of any of aspects 1-3, wherein the at leastone processor coupled to the memory is further configured to: provide acommon AS key and group specific or default signaling radio bearerconfiguration to the group of UEs; wherein the base station sends newSRB information to the group of UEs with integrity protection andciphering based on the common AS key and a group specific new SRBconfiguration.

Aspect 5 is the apparatus of any of aspects 1-4, wherein the grouphandover message comprises an RRC message comprising a list of RRCreconfiguration messages for each UE in the group of UEs, and wherein anRRC reconfiguration message in the list of RRC reconfiguration messagesindicates a difference with respect to a current configuration for arespective UE.

Aspect 6 is the apparatus of any of aspects 1-5, wherein the grouphandover message comprises MAC messages multiplexing RRC messages usingone or more LCIDs or C-RNTIs MAC control elements.

Aspect 7 is the apparatus of any of aspects 1-6, wherein each RRCmessage in the multiplexed RRC messages is based on a SRB and AS key ofa UE in the group of UEs, and wherein the SRB configuration is specificto the UE or comprises a default radio bearer configuration.

Aspect 8 is the apparatus of any of aspects 1-7, wherein each RRCmessage in the multiplexed RRC messages includes a delta configurationbased on default UE configuration for the target base station.

Aspect 9 is the apparatus of any of aspects 1-8, wherein a size of thegroup of UEs is based on an amount of the multiplexed RRC messagesallowed in a single TBS.

Aspect 10 is the apparatus of any of aspects 1-9, wherein the grouphandover message is transmitted in a groupcast message, and wherein thegroupcast message is transmitted at a specified or pre-defined time orlocation for the group of UEs.

Aspect 11 is the apparatus of any of aspects 1-10, wherein the at leastone processor coupled to the memory is further configured to: transmitan indication to one or more UEs of the group of UEs when to check thegroupcast message.

Aspect 12 is the apparatus of any of aspects 1-11, wherein the groupcastmessage is encrypted using a group common security key for the group ofUEs.

Aspect 13 is the apparatus of any of aspects 1-12, wherein the at leastone processor coupled to the memory is further configured to: provideconfiguration information for each UE in the group of UEs, wherein theconfiguration information for a UE in the group of UEs indicates achange in one or more configuration parameters for the UE relative to acommon configuration for the target base station, wherein the commonconfiguration for the target base station comprises a defaultconfiguration for the target base station applicable to each UE in thegroup of UEs or a full configuration for the target base station,wherein the configuration information is provided to the group of UEs inthe group handover message or in a downlink message prior to a handoverdecision.

Aspect 14 is the apparatus of any of aspects 1-13, wherein the grouphandover message one or more of: an indication to continue to use acurrent source cell configuration with the target base station, a newsecurity key for communication with the target base station, a NCC and aC-RNTI for the target base station, a new RTD value for the target basestation, or a new TA for the target base station.

Aspect 15 is an apparatus for wireless communication at a UE served by asource base station, comprising: a memory; and at least one processorcoupled to the memory and configured to: receive a group handovermessage comprising RRC configuration for one or more UEs transmitted toa group of UEs comprising the one or more UEs from the source basestation; and connect to a target base station using the RRCconfiguration based on the group handover message.

Aspect 16 is the apparatus of aspect 15, wherein the source base stationcommunicates with the group of UEs via a satellite.

Aspect 17 is the apparatus of any of aspects 15-16, wherein the grouphandover message is received in a RRC reconfiguration withsynchronization for the group of UEs, wherein the UE receives the grouphandover message in a cell specific common search space, and wherein atleast a portion of the group handover message is scrambled with a cellspecific group RNTI.

Aspect 18 is the apparatus of any of aspects 15-17, wherein the at leastone processor coupled to the memory is further configured to: receive,from the source base station, a common AS key and a group specific ordefault SRB configuration that is common to the group of UEs.

Aspect 19 is the apparatus of any of aspects 15-18, wherein new SRBinformation in the group handover message includes integrity protectionand cyphering based on the common AS key and a group specific new SRBconfiguration.

Aspect 20 is the apparatus of any of aspects 15-19, wherein the RRCreconfiguration comprises an RRC message comprising a list of RRCreconfiguration messages for each UE in the group of UEs, and wherein anRRC reconfiguration message in the list of RRC reconfiguration messagesthat is for the UE indicates one or more different parameters withrespect to a current configuration for the UE.

Aspect 21 is the apparatus of any of aspects 15-20, wherein the grouphandover message comprises a MAC message multiplexing RRC messages usingone or more LCIDs or C-RNTIs MAC control elements.

Aspect 22 is the apparatus of any of aspects 15-21, wherein the UEdecodes one RRC message in the multiplexed RRC messages that is directedto the UE.

Aspect 23 is the apparatus of any of aspects 15-22, wherein the UE usesa current UE specific SRB1 and AS security profile to attempt to decodethe multiplexed RRC messages to determine an RRC message intended forthe UE.

Aspect 24 is the apparatus of any of aspects 15-22, wherein the UE usesa default SRB1 to attempt to decode the multiplexed RRC messages.

Aspect 25 is the apparatus of any of aspects 15-25, wherein the one RRCmessage that is directed to the UE from the multiplexed RRC messagesincludes a delta configuration based on default UE configuration for thetarget base station.

Aspect 26 is the apparatus of any of aspects 15-25, wherein the UEreceives the group handover message in a groupcast message.

Aspect 27 is the apparatus of any of aspects 15-26, wherein the at leastone processor coupled to the memory is further configured to: check thegroupcast message for the group handover message based on a specified orpre-defined time or a location.

Aspect 28 is the apparatus of any of aspects 15-26, wherein the at leastone processor coupled to the memory is further configured to: receive anindication from the source base station about the groupcast message,wherein the UE receives the group handover message in the groupcastmessage in response to receiving the indication.

Aspect 29 is the apparatus of any of aspects 15-28, wherein the grouphandover message comprises an indication to continue to use a currentsource cell configuration with the target base station, and wherein theat least one processor coupled to the memory is further configured to:receive system information comprising common configuration andpre-compensation value for the target base station before connecting tothe target base station if information is not provided in handovermessage.

Aspect 30 is the apparatus of any of aspects 15-29, further comprising atransceiver.

What is claimed is:
 1. An apparatus for wireless communication of a basestation, comprising: a memory; and at least one processor coupled to thememory and configured to: transmit a group handover request for a groupof user equipment (UEs) to a target base station; receive a grouphandover acknowledgment from the target base station; and transmit agroup handover message to the group of UEs.
 2. The apparatus of claim 1,wherein the base station communicates with the group of UEs via asatellite, and wherein the group handover message is transmitted to eachUE in the group of UEs in a radio resource control (RRC) reconfigurationwith synchronization.
 3. The apparatus of claim 1, wherein the grouphandover message is transmitted to the group of UEs based on a cellspecific common search space, and wherein at least a portion of thegroup handover message is scrambled with a cell specific group radionetwork temporary identifier (RNTI).
 4. The apparatus of claim 3,wherein the at least one processor coupled to the memory is furtherconfigured to: provide a common access stratum (AS) key and groupspecific or default signaling radio bearer configuration to the group ofUEs; wherein the base station sends new signaling radio bearer (SRB)information to the group of UEs with integrity protection and cipheringbased on the common AS key and a group specific new SRB configuration.5. The apparatus of claim 1, wherein the group handover messagecomprises an RRC message comprising a list of RRC reconfigurationmessages for each UE in the group of UEs, and wherein an RRCreconfiguration message in the list of RRC reconfiguration messagesindicates a difference with respect to a current configuration for arespective UE.
 6. The apparatus of claim 1, wherein the group handovermessage comprises medium access control (MAC) messages multiplexingradio resource control (RRC) messages using one or more logical channelidentifiers (LCIDs) or cell radio network temporary identifiers(C-RNTIs) MAC control elements.
 7. The apparatus of claim 6, whereineach RRC message in the multiplexed RRC messages is based on a signalingradio bearer (SRB) configuration and access stratum (AS) key of a UE inthe group of UEs, and wherein the SRB configuration is specific to theUE or comprises a default radio bearer configuration.
 8. The apparatusof claim 6, wherein each RRC message in the multiplexed RRC messagesincludes a delta configuration based on default UE configuration for thetarget base station.
 9. The apparatus of claim 6, wherein a size of thegroup of UEs is based on an amount of the multiplexed RRC messagesallowed in a single transport block signal (TB S).
 10. The apparatus ofclaim 1, wherein the group handover message is transmitted in agroupcast message, and wherein the groupcast message is transmitted at aspecified or pre-defined time or location for the group of UEs.
 11. Theapparatus of claim 10, wherein the at least one processor coupled to thememory is further configured to: transmit an indication to one or moreUEs of the group of UEs when to check the groupcast message.
 12. Theapparatus of claim 10, wherein the groupcast message is encrypted usinga group common security key for the group of UEs.
 13. The apparatus ofclaim 1, wherein the at least one processor coupled to the memory isfurther configured to: provide configuration information for each UE inthe group of UEs, wherein the configuration information for a UE in thegroup of UEs indicates a change in one or more configuration parametersfor the UE relative to a common configuration for the target basestation, wherein the common configuration for the target base stationcomprises a default configuration for the target base station applicableto each UE in the group of UEs or a full configuration for the targetbase station, wherein the configuration information is provided to thegroup of UEs in the group handover message or in a downlink messageprior to a handover decision.
 14. The apparatus of claim 1, wherein thegroup handover message one or more of: an indication to continue to usea current source cell configuration with the target base station, a newsecurity key for communication with the target base station, a next hopchaining counter (NCC) and a cell radio network temporary identifier(C-RNTI) for the target base station, a new round trip delay (RTD) valuefor the target base station, or a new timing advance (TA) for the targetbase station.
 15. An apparatus for wireless communication at a userequipment (UE) served by a source base station, comprising: a memory;and at least one processor coupled to the memory and configured to:receive a group handover message comprising radio resource control (RRC)configuration for one or more UEs transmitted to a group of UEscomprising the one or more UEs from the source base station; and connectto a target base station using the RRC configuration based on the grouphandover message.
 16. The apparatus of claim 15, wherein the source basestation communicates with the group of UEs via a satellite.
 17. Theapparatus of claim 15, wherein the group handover message is received ina radio resource control (RRC) reconfiguration with synchronization forthe group of UEs, wherein the UE receives the group handover message ina cell specific common search space, and wherein at least a portion ofthe group handover message is scrambled with a cell specific group radionetwork temporary identifier (RNTI).
 18. The apparatus of claim 17,wherein the at least one processor coupled to the memory is furtherconfigured to: receive, from the source base station, a common accessstratum (AS) key and a group specific or default SRB configuration thatis common to the group of UEs.
 19. The apparatus of claim 18, whereinnew signaling radio bearer (SRB) information in the group handovermessage includes integrity protection and cyphering based on the commonAS key and a group specific new SRB configuration.
 20. The apparatus ofclaim 17, wherein the RRC reconfiguration comprises an RRC messagecomprising a list of RRC reconfiguration messages for each UE in thegroup of UEs, and wherein an RRC reconfiguration message in the list ofRRC reconfiguration messages that is for the UE indicates one or moredifferent parameters with respect to a current configuration for the UE.21. The apparatus of claim 15, wherein the group handover messagecomprises a medium access control (MAC) message multiplexing radioresource control (RRC) messages using one or more logical channelidentifiers (LCIDs) or cell radio network temporary identifiers(C-RNTIs) MAC control elements.
 22. The apparatus of claim 21, whereinthe UE decodes one RRC message in the multiplexed RRC messages that isdirected to the UE.
 23. The apparatus of claim 22, wherein the UE uses acurrent UE specific signaling radio bearer 1 (SRB1) and access stratum(AS) security profile to attempt to decode the multiplexed RRC messagesto determine an RRC message intended for the UE.
 24. The apparatus ofclaim 22, wherein the UE uses a default signaling radio bearer 1 (SRB1)to attempt to decode the multiplexed RRC messages.
 25. The apparatus ofclaim 22, wherein the one RRC message that is directed to the UE fromthe multiplexed RRC messages includes a delta configuration based ondefault UE configuration for the target base station.
 26. The apparatusof claim 15, wherein the UE receives the group handover message in agroupcast message.
 27. The apparatus of claim 26, wherein the at leastone processor coupled to the memory is further configured to: check thegroupcast message for the group handover message based on a specified orpre-defined time or a location.
 28. The apparatus of claim 26, whereinthe at least one processor coupled to the memory is further configuredto: receive an indication from the source base station about thegroupcast message, wherein the UE receives the group handover message inthe groupcast message in response to receiving the indication.
 29. Theapparatus of claim 15, wherein the group handover message comprises anindication to continue to use a current source cell configuration withthe target base station, and wherein the at least one processor coupledto the memory is further configured to: receive system informationcomprising common configuration and pre-compensation value for thetarget base station before connecting to the target base station ifinformation is not provided in handover message.
 30. The apparatus ofclaim 15, further comprising a transceiver.